| Spinal implant with elliptical articulatory interface -> Monitor Keywords |
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Spinal implant with elliptical articulatory interfaceRelated Patent Categories: Prosthesis (i.e., Artificial Body Members), Parts Thereof, Or Aids And Accessories Therefor, Implantable Prosthesis, Bone, Spine Bone, Having Opposed Bone-plates Which Moves Relative To One AnotherSpinal implant with elliptical articulatory interface description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070191952, Spinal implant with elliptical articulatory interface. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] This invention relates generally to improvements in spinal implants of the type designed for human implantation between adjacent spinal vertebrae. More particularly, this invention relates to an improved spinal implant prosthesis including a pair of implant components defining inter-engaged articulatory surfaces having a generally elliptical profile shape and designed to accommodate limited and/or controlled articulatory movement. [0002] Spinal implant devices are generally known in the art for surgical implantation between adjacent bony vertebral structures to correct or alleviate a number of clinical problems, such as degenerative disc disease, chronic back pain, spondylolisthesis, and others. In general terms, such spinal implants comprise a biocompatible construct formed from a relative high strength material such as titanium or cobalt chrome metal alloy, or a selected high strength ceramic, with a size and shape for intervertebral placement. In some designs, the implant has a porous region or regions adapted to receive autogenous or allogenous bone material, or otherwise defining a so-called porous bone ingrowth surface, for promoting bone ingrowth attachment of the implant device to the adjacent overlying and underlying vertebral structures. Such spinal implants are commonly used as fusion devices forming a substantially rigid interface between adjacent vertebral structures for alleviating specific patient symptoms. Alternative spinal implant designs comprise articulatory devices including upper and lower components adapted for respective fixation to overlying and underlying vertebral structures while defining an articulatory interface therebetween to maintain or restore normal or substantially normal patient movements. [0003] A variety of articulatory spinal implant devices are known in the art. By way of example, U.S. Pat. No. 5,401,269 discloses one articulatory implant device having inter-engaged concave and convex surfaces defined by curved radial or part-circular arches, wherein the radius of the curved arches is greater in the anterior-posterior direction relative to a smaller arch radius in the medial-lateral direction. These different sizes of the inter-engaged arches in the anterior-posterior vs. medial-lateral directions beneficially accommodates a limited range of axial rotation between the articulatory surfaces, while producing counteracting forces that tend to return the engaged surfaces toward a normal neutral or non-rotated position. In addition, the engaged arched surfaces further accommodate a range of angular displacement. However, such angular displacement, e.g., in the anterior-posterior direction, or in the medial-lateral direction, is not accompanied by a counteracting or re-centering force tending to urge the engaged surfaces back toward a normal neutral position. Physical stops are provided to prevent excessive angular displacement between the implant components. [0004] U.S. Pat. No. 6,113,637 discloses another articulatory spinal implant device having inter-engaged concave and convex surfaces of generally part-spherical or hemi-spherical shape, with the concave surface further including a centrally located cylindrical segment. This articulatory interface is designed to accommodate substantially unrestrained angular displacement as well as axial rotation between the engaged implant components, while additionally and beneficially permitting a range of fore-aft or anterior-posterior translation. Counteracting forces tending to resist over-displacement and tending to re-center the articulatory surfaces substantially in a neutral position are not present. [0005] There exists a need for further improvements in and to articulatory spinal implant devices, particularly wherein a range of angular displacement and/or axial rotation between engaged articulatory surfaces is accompanied by counteracting forces urging return movement of the engaged surfaces substantially to an initial or neutral position, and further wherein the engaged articulatory surfaces accommodate a range of anterior-posterior displacement. The present invention fulfills these needs and provides further related advantages. SUMMARY OF THE INVENTION [0006] In accordance with the invention, a spinal implant prosthesis defines an inter-engaged pair of concave and convex articulatory surfaces of elliptical profile shape, wherein these articulatory surfaces are elongated in the anterior-posterior direction and are comparatively shorter in the medial-lateral direction. In the preferred form, the anterior-posterior length of the concave surface is greater than the anterior-posterior length of the convex surface by a selected increment. These articulatory surfaces accommodate a limited range of anterior-posterior translation therebetween, and further accommodate a range of relative angular displacement and/or axial rotation while applying a corresponding counteracting or re-centering force urging the implant components back toward a substantially centered or neutral position. [0007] In the preferred form, the spinal implant comprises a pair of end plates, such as upper and lower end plates, formed from a suitable biocompatible construct and including affixation means for secure attachment respectively to adjacent overlying and underlying vertebral bone structures, as by means of fixation pins, bone cement, porous bone ingrowth surfaces, or a combination thereof. These end plates respectively define the inter-engaged convex and concave articulatory surfaces of elliptical profile. In one form, the upper end plate carries the convex articulatory surface for nested reception into and articulatory engagement with the concave surface carried by the lower end plate. [0008] Each of the articulatory surfaces is defined by the substantially elliptical profile shape which is longer in the anterior-posterior direction and shorter in the medial-lateral direction. More particularly, in the anterior-posterior profile, the convex articulatory surface has an elongated shape defined by a major axis extending generally in the anterior-posterior direction and sized for nested reception into the concave articulatory surface which has an incrementally longer size and shape, i.e., an incrementally longer major axis also extending generally in the anterior-posterior direction. In the medial-lateral direction, the convex and concave articulatory surfaces define comparatively smaller elliptical profiles, i.e., comparatively smaller major axes which extend generally in the medial-lateral direction, and may be of substantially uniform size. [0009] In use, the inter-engaged convex and concave articulatory surfaces of elliptical profile accommodate a range of relative angular displacement and relative axial rotation therebetween. However, as the two end plates are angularly displaced and/or axially rotated, the convex elliptical surface rides against the concave elliptical surface in a manner increasing the distance between the adjacent vertebral bone structures, thereby tensioning the prosthesis and producing a counteracting force or forces urging the components back toward a substantially centered or neutral position. In addition, the anterior-posterior size differential between the convex and concave articulatory surfaces accommodates a limited range of anterior-posterior translation therebetween. [0010] Other features and advantages of the invention will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS [0011] The accompanying drawings illustrate the invention. In such drawings: [0012] FIG. 1 is an exploded anterior or front perspective view of the spinal implant with elliptical articulatory interface embodying the novel features of the invention; [0013] FIG. 2 is an exploded anterior-posterior vertical sectional view of the spinal implant of FIG. 1; [0014] FIG. 3 is an anterior-posterior vertical sectional view similar to FIG. 2, but illustrating upper and lower components of the spinal implant in articulatory engagement; [0015] FIG. 4 is an exploded medial-lateral vertical sectional view of the spinal implant of FIG. 1; and [0016] FIG. 5 is a medial-lateral vertical sectional view similar to FIG. 4, but showing the upper and lower implant components in articulatory engagement. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT [0017] As shown in the exemplary drawings, a spinal implant referred to generally in FIGS. 1-5 by the reference numeral 10 is provided for surgical implantation into the intervertebral space between a pair of adjacent vertebral bone structures 12 and 14. The spinal implant 10 includes an upper component 16 and a lower component 18 adapted for respective affixation to the adjacent vertebral structures 12 and 14. The upper and lower components 16, 18 of the spinal implant 10 define inter-engaged convex and concave articulatory surfaces 20 and 22 of generally elliptical profile shape. These engaged articulatory surfaces 20, 22 are shaped to accommodate a limited range of angular displacement and/or axial rotation while producing a counteracting force or forces urging the components back toward a substantially centered or neutral position. In addition, the engaged articulatory surfaces 20, 22 accommodate a limited range of translation in an anterior-posterior direction. [0018] The articulatory spinal implant device 10 of the present invention includes the upper and lower implant components 16 and 18 formed from a suitable biocompatible material with a size and shape for respective engagement with and secure affixation to the overlying and underlying adjacent bony vertebral structures 12 and 14. In this regard, the bone-facing surfaces of the two implant components 16, 18 may include projecting fins, teeth or pins 24 or the like designed to provide immediate stable anchored engagement with the adjoining vertebral structures. The two implant components 16, 18 may also include respective upper and lower surfaces 26 defined by or otherwise suitably coated with a porous bone ingrowth structure or substance to permit and accommodate relatively rapid bone ingrowth and osteo-integration for long term stable affixation to the adjoining vertebral structures. [0019] The upper and lower implant components 16, 18 of the articulatory device 10 further define mutually facing bearing surfaces that are geometrically shaped for articulatory interengagement with each other in a manner intended to preserve and/or accommodate substantially normal anatomical intervertebral motion. The illustrative drawings show the upper implant component 16 to include an underside surface 28 in surrounding relation to the generally convex and centrally located articulatory surface or bearing member 20 protruding downwardly therefrom. This downwardly protruding convex articulatory surface 20 is received and movably supporting within the upwardly presented recessed or concave articulatory surface or bearing member 22 formed generally centrally within an upper surface 30 on the lower implant component 14. [0020] In accordance with the invention, the inter-engaged convex and concave articulatory surfaces 20 and 22 are both formed with a generally elliptical profile shape. More particularly, both articulatory surfaces 20, 22 are shaped to define a generally elongated elliptical profile in the anterior-posterior direction, and a comparatively smaller elliptical profile in the medial-lateral direction. Accordingly, as viewed best in FIG. 1, the convex articulatory surface 20 is thus shaped to define a generally football-shaped structure extending downwardly from the surrounding underside surface 28 of the upper component 16, for movable seated reception into the upwardly presented concave articulatory surface 22 of generally football-shape formed generally centrally within the upper surface 30 of the lower component 18. Continue reading about Spinal implant with elliptical articulatory interface... Full patent description for Spinal implant with elliptical articulatory interface Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Spinal implant with elliptical articulatory interface patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Spinal implant with elliptical articulatory interface or other areas of interest. ### Previous Patent Application: Intervertebral implants and methods of use Next Patent Application: System and method for replacing degenerated spinal disks Industry Class: Prosthesis (i.e., artificial body members), parts thereof, or aids and accessories therefor ### FreshPatents.com Support Thank you for viewing the Spinal implant with elliptical articulatory interface patent info. IP-related news and info Results in 0.26148 seconds Other interesting Feshpatents.com categories: Canon USA , Celera Genomics , Cephalon, Inc. , Cingular Wireless , Clorox , Colgate-Palmolive , Corning , Cymer , 174 |
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